The accumulator with oil-returning device, which is important component of the refrigeration system, is mainly used in the medium-sized or large-sized air conditioners or other refrigeration systems, and is mounted in front of the compressor and serves to receive, split, filtrate, circle oil, store refrigerant, thus plays a very important role in ensuring the normal operation of the system.
The accumulator includes a hermetically sealed container for storing temporarily refrigerant circulating in the refrigeration system circuit, an inlet pipe for introducing the refrigerant into the hermetically sealed container, an outlet pipe for discharging the refrigerant from the hermetically sealed container, and a filtering component with an oil-returning orifice and fixedly installed in the outlet pipe. The common accumulator further includes supporting board and gas-guiding component and so on. Generally, the refrigerant fluid in gas-liquid mixture state is introduced from the inlet pipe into the hermetically sealed container, wherein the gaseous refrigerant exists in a upper part of the hermetically sealed container due to smaller density, that is, the gaseous refrigerant is introduced into an inlet of the U-shaped outlet pipe and then enters into the compressor by flowing through the U-shaped outlet pipe under certain pressure difference. However the liquid mixture of the liquid refrigerant and the liquid refrigerating oil sinks at the bottom of the accumulator, such that the separation of gas from liquid in the mixture is achieved, and the liquid refrigerant fluid can be prevented from entering into the compressor and causes it damaged due to shock of the liquid refrigerant fluid.
At the bent arc portion of the U-shaped outlet pipe of the accumulator is arranged a filtering component including a filtering screen base with an oil-returning orifice and a filtering screen. Since there is a certain pressure difference between the inlet and outlet of the accumulator, when the gaseous refrigerant fluid flows through the bent arc portion of the U-shaped outlet pipe, negative pressure occurs at the oil-returning orifice of the filtering component, such that an appropriate quantity of the refrigerating oil can be introduced in the compressor through the outlet pipe, which enables the compressor being well lubricated and prevents the movable components of the compressor from being damaged due to poor lubrication.
The oil-returning capacity is an important property of the accumulator. If oil returning is performed properly, the following premises should be meet: (1) an appropriate pressure difference between the inlet pipe and the outlet pipe should be present, which is predetermined by the air conditioner factory during design stage; (2) appropriate-sized oil-returning orifice should be provided, as is generally determined in the air conditioner factory by experiment, and (3) in the case that the above two conditions are satisfied, it is necessary to have appropriate pressure difference at the oil-returning orifice of the filtering component, in order to ensure the refrigerating oil being drawn into the compressor. The pressure difference at the oil-returning orifice of the filtering component is generated by the following two factors, one of which is the gravity of the liquid refrigerant fluid and the liquid refrigerating oil per se depending on the quantity of the refrigerant and the refrigerating oil filled in the system and is difficult to adjust, the other one of which is the pressure difference resulting from a certain negative pressure at the filtering component generated when the gaseous refrigerant fluid flows in the outlet pipe. Thus, if it is needed to adjust the oil-returning capacity to provide the compressor with the best lubrication, it can be achieved only by adjusting the latter factor.
Chinese patent 200610036696.9 (publication number CN1900635A) discloses a technical solution, wherein a small oil-returning orifice with a certain diameter is directly formed in the outlet pipe, and a filtering component is welded in the small oil-returning orifice to form an oil-returning and filtering passage. The technical solution mainly has the following two disadvantages: (A) if the diameter of the oil-returning orifice and the diameter of the U-shaped outlet pipe remain unchanged (the diameter of the oil-returning orifice and the diameter of the U-shaped outlet pipe are very important parameters for the system, and in most cases are mainly designed by the air conditioner factory and will not be changed easily), in case that pressure difference of the system remains unchanged, it cannot be achieved to adjust the oil-returning capacity, and thus the product has poor versatility and is difficult to meet the requirements of various refrigeration system; and (B) since the oil-returning orifice is directly produced in the U-shaped outlet pipe, there may occur burrs which cannot be removed completely through checking or mechanical removal method, and thus dropped burr will enter into the compressor and cause the block in the compressor and the failure of the system.
Compared with the technical solution of Chinese patent 200610036696.9, Chinese Utility Model patent ZL200520102761.4 (publication number CN2804738Y) discloses an improved solution, in which a filtering component provided with an oil-returning orifice are soldered to the U-shaped outlet pipe, instead of the oil-returning orifice directly formed in the U-shaped outlet pipe. However, when the diameter of the oil-returning orifice and the diameter of the U-shaped outlet pipe are determined, the oil-returning capacity also cannot be adjusted and thus cannot meet the requirements of various refrigeration systems, in case that pressure difference of the system remains unchanged.
Therefore, there exists a need for an oil-returning device and an accumulator comprising the same capable of achieving appropriate oil-returning capacity in case that diameter of the oil-returning orifice and the diameter of the outlet pipe are given.